diff --git a/reference/strings/functions/trim.xml b/reference/strings/functions/trim.xml
index 1fe837f037..5c974fdc19 100644
--- a/reference/strings/functions/trim.xml
+++ b/reference/strings/functions/trim.xml
@@ -12,7 +12,7 @@
   <methodsynopsis>
    <type>string</type><methodname>trim</methodname>
    <methodparam><type>string</type><parameter>str</parameter></methodparam>
-   <methodparam choice="opt"><type>string</type><parameter>charlist</parameter></methodparam>
+   <methodparam choice="opt"><type>string</type><parameter>charlist</parameter><initializer>" \t\n\r\0\x0B"</initializer></methodparam>
   </methodsynopsis>
   <para>
    This function returns a string with whitespace stripped from the